when I try to constrain lines in a sketch to be equal length I cannot select the lines. I can select them to do other functions but not equal length. The pop up window appears but nothing will highlight to be selected.

I'm getting the same problem with my 2013 SP0. Initially my test was in a standalone sketch (with no part). Picking lines to execute the Equal Length constraint works fine at the standalone sketch level.

Created a simple block part, inserted a sketch, chose a face of the block for the plane, drew a few lines and exactly as Chris experienced it would not allow me to pick the lines to execute the Equal Length constraint. No problem with picking those same lines for other constraints such as Horizontal or Vertical.